Munich: Police in southern Germany said on Sunday that that the motive for a stabbing attack on a high-speed train the previous day was still unclear, but that the main suspect was suffering from psychological problems.The local head of police, Norbert Zink, told reporters that the attacker was quickly apprehended without putting up resistance. He thanked other passengers "who tried to prevent the suspect from carrying out further actions.” Four people were injured in total by the attacker, his deputy Thomas Schoeniger said at the press conference in Neumarkt. In the order that they were attacked, the victims were aged, 26, 60, 60 and 39.The two younger victims were still in hospital, he said.The head of the criminal department, Sabine Nagel, said there was "no evidence of an Islamist background” to the attack. (DPA)